gstreamer: Correctly don't allow too limited bit rates
gstreamer: Correctly don't allow too limited bit rates

The check to limit too low bit rates was setting encoder->bit_rate
instead of bit_rate. However after some lines bit_rate was used
to set encoder->bit_rate basically removing the lower threshold.

Signed-off-by: Frediano Ziglio <55d48b080b2e443e395cde84d2c83b135a4ff48e@redhat.com>
Acked-by: Francois Gouget <6b915da68578f6eb004fe99432b967565fc9be8f@codeweavers.com>

fgouget/spice,fgouget/spice,fgouget/spice,fgouget/spice